1. Field of the Invention
This invention relates to the field of magnetic imaging. More specifically, the present invention comprises a system used to capture images of the magnetic flux leakage of faults located on steel reinforcing tendons embedded in concrete or grout.
2. Description of Related Art
Bridges and other structures are supported using long, embedded steel tendons. Typically, a steel reinforcing tendon is embedded in concrete or grout in order to account for the lack of tensile strength of a concrete. Often, these steel tendons are damaged. However, since the steel tendons are embedded in concrete or grout, the fault is typically difficult to locate and evaluate. The damage can be caused by human sources or corrosion. In order to decide whether replacement is necessary, the cause of damage must be determined. This can be done by destroying the concrete or grout surrounding the steel tendon or by a non-destructive imaging method. Typically, if the cause of the fault on the tendon is manmade, then replacement is not necessary. However, if the cause of the fault is corrosion, then the tendon is typically addressed or replaced. This is because corrosion is progressive in nature, whereas a cut or hole caused by a worker is not progressive.
Destroying the grout and/or concrete surrounding a steel tendon for inspection is time-consuming, potentially dangerous, and expensive. This method of inspection is not plausible for periodic maintenance of steel tendons. A non-destructive method for inspection greatly reduces time and cost of maintenance. In addition, a destructive method of inspection may jeopardize the integrity of the supporting column, and possibly the entire structure in which it supports.
Thus, the need for a non-destructive method for imaging steel reinforcing tendons has been recognized. It is critical for the safety of the public to have the capability to evaluate the state of a steel reinforcement tendon embedded in concrete or grout. In addition, it is important to decipher the cause of the fault in the tendon. If the cause of the fault is not established, workers may destroy a column for a non-progressive fault, such as a nick or a cut. Since it is not necessary to replace a tendon for a manmade nick, cut or hole, this would be an extreme waste of resources. Thus, using a destructive method of inspection is an extremely costly method of evaluating the state of a steel tendon.
There are methods of inspection used to evaluate the steel tendons embedded in grout or concrete in the prior art that are non-destructive. However, these methods have a number of drawbacks. First, the prior art methods are limited in the data acquired. Second, those methods require significant time and expertise to setup and interpret the data acquired. Finally, the cost to setup and extract useful information from that data acquired from the prior art methods is expensive. The present invention solves these and other problems, as will be described more particularly in the following text.